Process of bleaching mineral oils and fats



Patented Jan, 6, 193B WILHELM POSTH AND FRANZ BESEMANN, OF BITTEBFELD, GERMANY, AS SIGNORS TO "1- USTBIE AKTIENGFSELLSGHAIFT, OI FRANKFORT-ON-THE-HAIN,

PROCESS OF BLEACHING MINERAL OILS FATS No Drawing. Application filed August 19, 1927, Serial No. 214,214, and in Germany July 21, 1926.

This invention relates to a method of bleaching mineral oils and fats and is more particularly concerned with the treatment of these substances for bleaching purposes after other, especially sulfur containing, impurities, such as the so-called skunk compound, have been removed, preferably by the known acid alkali treatment.

The products thus obtained frequently do not display the clearness generally required by the consumers and it has been already proposed to cure this by a treatment with hypochlorites. In this case, however, the difficulty arises that the bleaching liquor which acts but slowly in an alkaline solution is insufliciently utilized. On the other hand, when providing for the presence of a certain quantity of acid in the solution or considerably increasing the temperature, so as to prompt the formation of hypochlorous acid, secondary reactions of a detrimental nature are produced, these being soinetimes also followed by a subsequent darkening of the oil or fat.

Now we have found that by adding substances which exert an accelerating action on the decomposition of hypochlorites into chloride and free oxygen, such as the salts of heavy metals, for instance, nickel, cobalt, copper &c, the bleach is easily initiated without the addition of an acid and a thorough utilization of the hypochlorite is brought about.

Furthermore we have found that any means for removing the caustic alkali contents in the hypochlorite solution andserving to partially transform the hypochlorite to hypochlorous acid, as for instance a blCfl-I bona-te or other substance of weak acid character accelerates and enhances the accomplishment of the bleach.

Therefore our process for bleaching any ordinary or prerefined mineral oil or fat-the latter in the liquid state at a correspondingly elevated temperaturecomprises a treatment with an aqueous hypochlorite solution in the presence of means for accelerating the decomposition of the hypochlorite .into its chloride and free oxygen, which means according to our invention consists in the simul- The nickel hypochlorite is immediately decomposed acording to the following equatron: I

. Our improved process may be illustrated by the following examples. Taking into account the great variety and variability of materials to be treated it must be understood that within our general rule neither a speci fied rule as regards the composition of the bleaching solutions nor a schedule as regards the numerical proportions between bleaching goods and bleaching means can be given.

0111 examples correspond only to single cases chosen at random and the exact proportions of the metal oxids, the concentration of the hypochlorite solution and "the addition of acidulating means must be ascertained in any special case by preliminary experiments, which however are easily performed.

Examples 1. 1000 kilograms of a mineral oil pre-refined by acids or alkalies in the well known manner-are mixed anduthoroughly stirred with kilograms of soda bleaching liquor containing 150 grams of available chlorine per liter. While stirring continually 500 grams of nickel sulfate dissolved in 50 liters of water are added. From time to time the available chlorine contents of a sample is tested. After the reaction is completed, which is indicated by the consumption of the available chlorine, the oil is heated to about C. to facilitate the separation of the emulsion and washed with water.

2. 1000 kilograms of a distilled lubricating oil are at first treated with an acid and an alkali and then with a bleaching solution made in the following manner: 50 kilograms of soda bleaching liquor containing 150 grams of available chlorine per liter are mixed with 400 grams of cobalt sulfate dissolved in 50 liters of water and 2 kilograms of sodium bicarbonate dissolved in 20 liters of water. This bleaching solution is added to the mineral oil while stirring. During the bleaching operation stirring is continued. After consumption of the available chlorine the oil is further treated as described in the preceding example.

3. 1000 kilograms of paratfin are melted.

40 kilograms of a bleaching solution contain-,

ing about 150 grams of available chlorine per liter are diluted with an equal quantity of water and gradually added to the oil. Hereupon 150 grams of nickel sulfate dissolved in 2 liters of water are added and the reaction mixture is stirred while performing the bleaching action. As soon as no more active chlorine is ascertainable the oil is washed with hot water until neutral reaction is attained. The para-flin after being separated from the Water is allowed to solidify.

We claim 1. The process of bleaching pre-refined mineral oils which comprises treating them with an aqueous hypochlorite solution in the presence of a heavy metal salt capable of accelerating the decomposition of hypochlorites into chlorides and oxygen, heating the resulting mixture to about 60 C., separating the oils from the spent bleaching bath and washing said oils. i

2. The process of bleaching pro-refined mineral oils which comprises treating them with an aqueous hypochlorite solution in the presence of a salt of a metal selected from the group consisting of copper, nickel and cobalt, which salt is capable of accelerating the decomposition of hypochlorites into chlorides and oxygen, heating the resulting mixture to about 60 (3., separating the oils from the spent bleaching bath and washing said oils.

3. The process of bleaching pre-refiued mineral oils which comprises treating them with an aqueous hypochlorite solution in the presence of nickel sulfate, heating the resulting mixture to about 60 G, separating the oils from the spent bleaching bath and washing said oils.

4. The process of bleaching mineral Oils which comprises subjecting said oils to a usual acid-alkali refining treatment, treating the refined oils with an aqueous hypochlorite solution in the presence of a heavy metal salt capable of accelerating the decomposition of hypochloritesv into chlorides and oxygen, heating the resulting mixture to about 60 C.,

separating the oils from the spent bleaching bath and washing said oils.

5. The process of bleaching mineral oils which comprises subjecting said oils to a usual acid-alkali refining treatment, treat ing the refined oils with an aqueous hypochlorite solution in the presence of a salt of a metal selected from the group consisting of copper, nickel and cobalt, which salt is capable of accelerating the decomposition of hypochlorites into chlorides and oxygen, heating the resulting mixture to about 60 (1, separating the oils from the spent bleaching bath and washing said oils.

6. The process of bleaching mineral oils which comprises subjecting said oils to a usual acid-alkali refining treatment, treat-- ingthe refined oils with an aqueous hypochlorite solution in the presence of nickel sulfate, heating the resulting mixture to about 60 C., separating the oils from the spent bleaching bath and washing said oils.

7. The process of bleaching mineral oils which comprises subjecting said oils to a usual acid-alkali refining treatment, treating the refined oils with an aqueous alkaline hypochlorite solution containing a bicarbonate, whereby the alkalinity of the bleaching solution is reduced, in the presence of a salt of a metal selected from the group consisting of copper, nickel and cobalt, which salt is capable of accelerating the decompositin of hypochlorites into chlorides and oxygen, heating the resulting mixture to about 60 0., separating the oils from the spent bleaching bath and washing said oils.

8. The process of bleaching pre-refined mineral oils which comprises treating them with an aqueous hypochlorite solution, con-- taining about 150 grams of available chlorine per liter of solution, in the presence of a heavy metal salt capable of accelerating the decom-- position of hypochlorites into chlorides and oxygen.

9. The process of bleaching pre-refined mineral oils which comprises treating them with an aqueous hypochlorite solution, containing about 150 grams of available chlorine per liter of solution, in the presence of a salt of a metal selected from the group consisting of copper, nickel and cobalt, which salt is capable of accelerating the decomposition of hypochlorites into chlorides and oxygen.

10. The process of bleaching pro-refined mineral oils which comprises treating them with an aqueous hypochlorite solution, containing about 150 grams of available chlorine per liter of solution, in the presence of nickel sulfate.

11. The process of bleaching pre-refined mineral oils which comprises treating them with an aqueous hypochlorite solution, containing about 150 grams of available chlorine per liter of solution, in the. presence of nickel sulfate, heating the resulting mixture to about 60 (1, se arating the oils from the spent bleaching ath and washing said oils.

In testimony whereof we have hereunto set our hands.

wmLM POSTHI FRANZ BESEMANN. 

